1. Field of the Invention
This invention relates to fluid energy conversion systems, and more specifically one powered with Magnus Rotors.
2. Description of the Prior Art
Air pressure at the earth's surface is 14.7 lbs./sq. inch. This is about a metric ton/sq. ft. So a cubic foot of air weighs about a metric ton. If this cubic ft. of air is made to move 10 miles/hour the power developed is over 56 horsepower. So theoretically wind energy can supply all man's energy needs. There has been some progress in extracting this energy. In order to do so at 100% efficiency a perfect vacuum must be somehow operatively connected with normal air pressure. Airfoils are used to cause a mild pressure difference which is enough to lift aircraft and, in the form of a propeller, to spin wind turbines to produce electrical energy. But wind turbine efficiency is severely limited since a great deal of the incoming wind energy blows through the propeller arc without affecting performance.
The general problem is to increase as much as possible the coefficient of drag/lift so more power can be produced over the same frontal area of whatever shaped energy collector is placed in the wind stream.
A Magnus Rotor is a spinning cylinder placed so its axis is normal to airflow. If it is spun so the peripheral velocity is the speed of sound then, with no wind, air pressure next to the cylinder drops to zero. Spun in a wind the air is sped up on one side of the cylinder and retarded on the opposite side so the cylinder is drawn towards the vacuum created by the spinning and pushed on the cylinder's opposite side towards the vacuum.
According to Flettner (U.S. Pat. No. 1,674,169) and specifically claims 20-24 and FIGS. 27,28 we see a wind machine with airfoil blades replaced by Magnus Rotors. In the Figures we see the plane of the rotors tilted backwards. This is so a rotor does not come close to the supporting pole as a rotor is made to swing past this supporting pole.
Turning to Hanson (U.S. Pat. No. 4,366,386) we see in FIG. 1 an arrangement where the Magnus Rotors are located so the wind strikes the supporting pole before it strikes the Rotor. These features are for the purpose of reducing the effect of turbulence on the Magnus Rotor.
In Holland (U.S. Pat. No. 4,582,013 which is based on experiments done by Holland under U.S. Dept. of Energy grant FG46-79R610969 issued June, 1981) various conclusions were reached:
1. end plates fixedly attached to the rotor and larger in diameter than the Rotor itself and were spun at the same angular velocity as the Rotor were ineffective in reducing induced drag on the end surfaces of the Rotor. See columns 27,28.
2. Designing a Rotor which is made to spin rapidly and at the same time be made to whirl rapidly around a central hub produces singular drag problems. These and other problems were recognised in the Holland experiments and are addressed in the present invention.
Flettner, Hanson and Holland have their Magnus Rotors' external skin passed close to their supporting poles, cutting down on the possible velocity at which the Magnus Rotor can be revolved. The faster the Rotor is revolved the more power can be developed by their inventions.
It is the principal object of this invention to keep the external skin of a Magnus Rotor as far away from the support structure as is practical to maximize power output of an operatively connected wind energy conversion system.